SYNOPSIS

DESCRIPTION

ffproxy is a filtering HTTP/HTTPS proxy server. It is able to filter by
host, URL, and header. Custom header entries can be filtered and added.
It can even drop its privileges and optionally chroot(2) to some
directory. Logging to syslog(3) is supported, as is using another
auxiliary proxy server. An HTTP accelerator feature (acting as a front-
end to an HTTP server) is included. Contacting IPv6 servers as well as
binding to IPv6 is supported and allows transparent IPv6 over IPv4
browsing (and vice versa).
Remind that there is an alternative to command line options by using
configuration files. See ffproxy.conf(5) and sample.config for details.
It allows options that are not available on command line.
The following command line options are recognized. They specify general
settings like IP to bind to or place of the db/ and html/ directories.
Note that arguments to options must be seperated from the option by
spaces, as are such options from each other.
-pport Bind to port. Default is 8080.
-cip|hostname
Bind to IPv4. Default is any IPv4.
-Cip|hostname
Bind to IPv6. Default is any IPv6.
-lchilds
Maximum number of child processes to be forked. That is, the
maximum number of concurrent requests allowed. Default is 10.
-uuid|user-ggid|group
Change UID and GID. Both options must be used. Default is not
changing UID and GID.
-rdir Change root chroot(7) to dir. Used in conjunction with -u and
-g. Because ffproxy drops its privileges and chroots after
reading the configuration files, -D should be set to . (the
current dir). It might need /etc/resolv.conf copied as
etc/resolv.conf in its working directory. Example: ‘‘# cd
/var/ffproxy ; /usr/local/bin/ffproxy -r /var/ffproxy -D . -d -u
proxy -g proxy -f ""’’
-xip|hostname
Specify IP (or hostname) of an auxiliary proxy server that the
program will forward requests to. Used together with -X.
-Xport Port number of auxiliary proxy.
-Ddir Location of the db/ and html/ directories. For example,
specifying -D /var/ffproxy tells the proxy to search for db/
files in /var/ffproxy/db/ and html/ files in /var/ffproxy/html/.
-aip|hostname
Auxiliary forward HTTP server to use (see section HTTP
ACCELERATOR).
-Aport Port to use for above. Defaults to 80.
-npiddir
directory to store file ffproxy.pid with ffproxy pid inside.
Default is /var/run-fconfigfile
User configuration file to load. Please note that command line
options get overwritten by set configuration file options.
Default location is /etc/ffproxy/ffproxy.conf. Read
ffproxy.conf(5) for details. Use -f "" to disable configuration
files.
-d Run as daemon.
-s Be silent. Don’t log to syslog.
-4 Use IPv4 only. Do not try contacting servers via IPv6.
-b Don’t bind to IPv4. Might be needed under Linux 2.4, due to a
‘‘Feature’’ IPv6 binds to IPv4, too. Try using this option or
bind to specific IPv6 address via -C.
-B Don’t bind to IPv6.
-h Show usage information.
-v Display version number.

THEDB/DIRECTORY

The db/ directory contains files that control the behaviour of ffproxy.
The files for filtering are prefixed by ‘filter’. Access to the proxy
server is controlled by files with prefix ‘host’.
Filtering
Requests or header entries to be filtered are matched by extended regular
expressions or case insensitive by strings.
ffproxy is able to filter requests by host, header, remote header, and
URL. The specific files are
filter.host.matchfilter.header.dropfilter.header.entryfilter.header.matchfilter.rheader.dropfilter.rheader.entryfilter.rheader.matchfilter.url.match
Files ending in ‘drop’ specify requests to be completely filtered
(dropped). Files ending in ‘entry’ specify header entries to be removed
from the header. They are matched case insensitive without extended
regular expressions. Files ending in ‘match’ specify extended regular
expressions to be matched against header entries, host, or URL.
Adding custom header entries is also supported. The entries of file
filter.header.add will be added to every outgoing request.
AccessControl
Access to the proxy is controlled through the files prefixed ‘host’.
host.dyndns contains host names with dynamic IPv4 addresses. The host
names are resolved to IPv4 addresses and compared to the client’s IP. If
it matches, access is granted.
host.ip contains static IPv4 and IPv6 address.
host.name contains official hostnames (reverse lookup).
Except for host.dyndns, the files contain extended regular expressions.
If any of the entries matches, access is granted.
Layoutofdb/Files
Every mentioned file above must exist, although it may be empty. Every
entry is exactly one line. Empty lines are ignored, as are lines
beginning with a # (comments).
The location of the db/ directory may be specified by an argument to the
command line option -D. If this option and configuration file option
db_files_path are not used, ffproxy will search for db/ and html/ in
/usr/share/ffproxy.
ffproxy comes with sample db/ files. They also contain needed and
suggested entries, as described next.
Suggesteddb/fileentries
The file filter.header.entry should contain following entries for the
program’s proper operation
Accept-Encoding:
Accept:
Connection:
Proxy-Connection:
Host:
First two lines are needed for browsers that send out Accept*: Headers
but don’t understand encoded data coming back from the proxy. Host: has
to be removed, since proxies require absolute URIs (Host: is redundant).
filter.header.add should contain
Connection: close
Proxy-Connection: close
We removed the two entries through filter.header.entry and now implant
our own to force disconnection after each request.
filter.rheader.entry should contain
Connection:
Proxy-Connection:
Whatever the server answered, we remove it.

THEHTML/DIRECTORY

This directory contains files with HTTP header and HTML that are sent to
the user’s browser if either an error occured or a request was filtered.
In the files, the variable $u will be replaced by the URL, $h by the host
to connect to, and $c by the hostname of the client.
Since the files are loaded into memory for faster execution, the size of
each file is limited to about 8 kB (what is more than enough, the default
files are under 1 kB).
The specific files are (every file must exist)
connect Connection failed (503)
filtered Request filtered (200)
invalid Invalid request (400)
post Unable to post data (400)
resolve Resolve error (503)

HTTPACCELERATOR

ffproxy may also be used as a HTTP accelerator, that is, connecting to
just one HTTP server and beeing a front-end to that. Use accel_host and
accel_port in configuration file or command line options -a and -A to use
this feature.
Default behaviour is *not* sending Host: header to allow insertion of a
custom one via filter.header.add (see section THE DB/ DIRECTORY) or
keeping the original one used by connecting client (‘Host:’ hast to be
removed from default filter.header.entry, of course). To change this,
use ‘accel_user_host no’ in the configuration file. ‘‘Host:
accel_host:accel_port’’ will be used then.

TRANSPARENTOPERATION

It is possible to redirect all HTTP traffic, that is, traffic to port 80,
to the proxy’s listening port. It will then transparently act as a HTTP
proxy, the client not even knowing it is connecting to a proxy.
On OpenBSD one could enable this by adding a line like
rdr on rl0 proto tcp from any to any port 80 -> 127.0.0.1 port 8080
to /etc/pf.conf. In this example, rl0 is the local interface. All
traffic coming from rl0 directed to port 80 (HTTP standard port) is sent
to 127.0.0.1:8080 where ffproxy is supposed to be listening.

KEEPALIVE

The program supports keep alive on client to proxy connections. This is
used automatically by default and may be disabled by setting
‘use_keep_alive no’ in the configuration file.

HTTPSOPERATION

The proxy allows HTTPS proxying via implementation of the CONNECT request
method. By default, only port 443 is allowed for CONNECT. This may be
changed by using ‘unrestricted_connect yes’ in the configuration file.
Timeout may also be tuned by ‘timeout_connect seconds’.

RELOADINGCONFIGURATION

Send a SIGHUP to the pid of the ffproxy master process to let it reload
db/ files, html/ files, *and* configuration file. If no configuration
file was specified, /etc/ffproxy/ffproxy.conf is tried. Of course, only
some changes to the program can be done at runtime. See ffproxy.conf(5)
for details on options that may be changed at runtime.
ffproxy write its pid file ffproxy.pid in the directory specified by the
command line parameter -n or the pid_dir setting in config file. Default
is /var/run.

LOGGING

By default, the proxy logs incorrect and filtered requests. To log all
requests, use the configuration file keyword ‘log_all_requests yes’.
Please make sure that you seperate the programs log output from that of
other programs by modifying syslog.conf(5), since the output is very
noisy.

FILES

Behaviour of ffproxy is determined by
· startup options given either on the command line or read from
configuration files -- /etc/ffproxy/ffproxy.conf is loaded by
default.
· the files in db/ which specify filtering options and who is allowed
to connect and use ffproxy